Servius Tullius was the sixth king of ancient Rome, traditionally believed to have reigned from around 578 to 535 BCE. He is credited with significant reforms, including the establishment of the Census, which organized Roman citizens based on wealth and social class. This system laid the groundwork for the later Roman Republic. Additionally, Servius Tullius is known for the construction of the Servian Wall, a defensive barrier that protected the city of Rome. His reign is often associated with the expansion of Roman territory and the strengthening of its political structure, contributing to the city's growth and stability.